1. Field of the Invention
The present invention relates generally to storage area networks. Particularly, the present invention relates to configuring a server form a storage area network.
2. Description of the Related Art
Booting is a process that starts operating systems when a computer system is turned on. It is an iterative process of loading the installed operating system code from a storage device into computer memory. For example, in an IBM® compatible personal computer, the Basic Input/Output System (BIOS) is loaded first. The BIOS initializes the computer hardware and reads the code from a storage device necessary to begin the next stage of booting. Next, the hardware setup is completed and a fully functional operating system is loaded in the memory. The boot process can be invoked from a direct attached disk, e.g., a hard-drive, a CD-ROM, etc., from a local area network, e.g., Ethernet, or from a storage area network (SAN), e.g., Fibre Channel SAN, iSCSI SAN, etc.
Booting from a SAN offers several advantages over booting from a direct attached disk—a few of which are discussed here. Booting from SAN alleviates the necessity for each computer system, e.g., a server, to house a local disk drive—resulting in savings in space due to server consolidation and savings in power consumption due to fewer hardware components. Further, operating system images can be stored to disks on the SAN, which allows all upgrades and fixes to be managed at a centralized location. This eliminates the need to manually install upgrades on each system. In instances of server failure, a new server can be quickly deployed into operation by replicating the configuration information of the failed server onto the new server and allowing the new server to boot from the SAN. This results in smaller downtimes compared to direct attached disk based servers where the new server would require the time consuming task of reinstalling the operating system on the disk drive.
In Fibre Channel SANs, for example, servers communicate with the SAN through host bus adaptors (HBAs). Typically, the HBA BIOS contains data and instructions that enable the server to locate the boot disk on the SAN. The data may include, among other things, the world wide name (WWN) and the logic unit number (LUN) of the boot device. Prior to deployment of the server, the firmware on the HBA is configured to include the WWN and the LUN of the storage device. Once the server is connected to the SAN, the HBA logs on the SAN and subsequently communicates with the boot device associated with the stored WWN and LUN to begin the boot process.
Occasionally, the data and instructions, related to locating the boot disk, stored on the HBA may have to be updated. For example, failure of the currently assigned boot disk may require that the server boot from another boot disk at a different location in the SAN. Therefore, the WWN and the LUN, related to the boot disk, stored in the HBA needs to be updated. Also, changes in the zoning configuration of the SAN may result in certain boot disks to be removed from the member list for that zone, which, in turn, requires that the information on the HBA be updated. Updating the server HBA firmware each time to reflect changes made elsewhere in relation to the SAN and the target boot device is time consuming and cumbersome.